Canadian Study Finds Significant Reduction In Opioid Use Linked To Medical Cannabis Authorizations

A recently released Canadian study has found that authorizations to use medical cannabis for chronic pain patients correlated to a reduction in opioid use among those to whom they are prescribed. A report on the research, “Opioid use in medical cannabis authorization for adult patients from 2013 to 2018: Alberta, Canada,” was published earlier this month in the journal BMC Public Health.

In their background statement for the abstract of the study, researchers affiliated with the University of Alberta and the University of Toronto wrote that the over-prescription and widespread diversion of opioid medications has led to an epidemic of misuse and abuse in both Canada and the United States. As a result, identifying suitable medical alternatives to opioids and helping patients reduce their intake of the powerful painkillers has become a critical area of investigation.

“An increasing body of literature suggests that medical cannabis may decrease chronic pain, be a potential substitute for opioids and act as a contender for decreasing patients’ opioid usage,” the authors of the study wrote. “Known as the ‘opioid-sparing effect,’ recent studies have emphasized the analgesic properties of medical cannabis—and that concomitant use with cannabis may potentially show a significant reduction in overall reliance of opioid usage—and consequently, lead to an improved quality of life.”

To conduct the research, the investigators assessed the relationship between the use of medical cannabis and the consumption of opioid painkillers. The investigators analyzed medical cannabis use and opioid consumption among chronic opioid users, including more than 5,300 patients authorized to use medical cannabis and a group of matched controls who did not receive medical cannabis authorizations. The researchers evaluated the study subjects’ change in weekly opioid consumption, as measured by the oral morphine equivalent (OME). Patients’ use of opioids for the 26 weeks before and 52 weeks after medical cannabis authorization was studied.

Greatest Reduction In Opioid Use Observed In High-Dose Patients

An analysis of the data found that medical cannabis authorization had mixed results on short-term opioid use. Overall, however, subjects with a medical cannabis authorization reduced their use of opioid medications at a rate greater than matched controls. The greatest reduction in use appeared to be in patients who started with a high dosage of opioids.

Among those prescribed high doses of opioids (OME > 100), there were significant reductions in opioid consumption in relation to matched controls. However, the subjects prescribed lower doses of opioids before they received an authorization for medical cannabis failed to show a statistically significant reduction in their opioid intake relative to the matched controls.

“This short-term study found that medical cannabis authorization showed intermediate effects on opioid use, which was dependent on initial opioid use,” the authors of the study wrote in their conclusion. “Greater observations of changes in OME appear to be in those patients who were on a high dosage of opioids (OME > 100); however, continued surveillance of patients utilizing both opioids and medical cannabis is warranted by clinicians to understand the long-term potential benefits and any harms of ongoing use.”

The researchers noted that the research is consistent with other studies that have shown a reduction in opioid use in relation to access to medical cannabis.

“Overall, our findings may contribute ongoing evidence for clinicians regarding the potential impact of medical cannabis to reduce the opioid burden among patients,” they wrote.

Earlier this year, a team of researchers from the University of Toronto reported that the number of opioid prescriptions in Canada declined after recreational cannabis became legal in 2018.

“Our findings support the hypothesis that easier access to cannabis for pain may reduce opioid use for both public and private drug plans,” the researchers wrote.